Technical Field
The present invention relates to an opening method and device thereof.
Related Art
An opening device is being implemented in which, when collecting test samples from metal coils of wound metal sheet, an opener board is placed in contacted with the entire width of the outer peripheral surface of a metal coil, the leading end portion of the metal coil is opened (unwound; separated from the coil), and a sample is cut with a cutting device (see, for example, Japanese Patent Application Laid-Open (JP-A) No. S59-174218).
The opener board is a rectangular shaped board, and the leading end portion of the metal sheet configuring the metal coil is lifted up onto the opener board by placing the leading end of the opener board in contact with the outer peripheral surface of the metal coil, and rotating the metal coil. The metal sheet is pulled out along the opener board. A test sample is collected by cutting the metal sheet pulled out from the metal coil over the opener board in this manner using gas or a blade.
However, when opening the metal coil using the opener board, the metal sheet that was wound curved into the metal coil is straightened out along the opener board. As a result, a high bending load acts on the metal sheet remaining in the metal coil, plastic deformation occurs, and the metal sheet does not return to its original shape after rewinding. There is accordingly an issue that plastic deformation occurs at the leading end portion of the metal coil when strapping, with the possibility of slackness occurring.